We propose to study the effects of maternal obesity, weight gain and diet during pregnancy on offspring fat mass, fat distribution, vascular and metabolic function. Specifically we will: 1. Determine the magnitudes of the associations of maternal BMI, weight gain and diet during pregnancy with offspring adiposity (DXA assessed fat mass and fat distribution), vascular function (blood pressure, pulse pressure and endothelial function) and metabolic function (fasting glucose, insulin and lipids). 2. Determine whether any association between maternal factors and offspring outcomes represent a specific intrauterine effect by comparing the maternal-offspring associations to equivalent paternal-offspring associations. 3. Examine the role of intrauterine growth, offspring nutrition and physical activity in explaining the associations of maternal obesity, weight gain and diet during pregnancy with offspring obesity, metabolic and vascular function. These aims and objectives will be achieved using data from a large, population-based cohort of children recruited before birth and followed up to the present day. The study - the Avon Longitudinal Study of Parents and Children (ALSPAC) - recruited 14,541 pregnant women in 1991-92. Of these 13,617 women delivered a live singleton child who was still alive at one year after birth. Of these singleton births we have measurements of offspring outcomes: fat mass and fat distribution determined by Dual Emission X-Ray Absorptiometry (DXA), blood pressure, endothelial function determined by high-resolution ultrasound imaging and metabolic function determined by fasting glucose, insulin and lipids up to age 15 years on over 7,000. Further, DNA has been extracted on both mothers and their offspring. A large amount of data has been collected on both parents, including their weight and height and diet in pregnancy. This work will make an important contribution to our understanding of the developmental origins of obesity and its associated vascular and metabolic abnormalities. It will provide the necessary evidence for the development of randomised controlled trials concerned with examining the effectiveness of brief interventions during the intrauterine period (a key developmental period for obesity) in the prevention of future obesity.